Beaten by mere seconds!
Blindly dumping chlorine is like painting in the dark. If there's astronomical CYA, you may never clear it before vacation's over! pH could be whacked, too.
Call the rental office/property manager and complain. They probably have a pool service - let them get on the phone and get an emergency call made.
If it's a holiday rental, and not just some friends letting you use their second home, they're probably considered a public pool, same as a motel. Threaten to summons the health department. Nobody wants some officious government busybody poking around.
If you insist on doing it yourself, drop a few bucks on a test kit or take a sample to the pool store. If you buy a kit similar to what you have at home, you just got some refills in advance.